Canada's Transportation Safety Board says it is launching an investigation after the implosion of the Titan submersible left all five passengers dead
In the US, a separate probe will be launched involving the American counterpart and US Coast Guard
Tributes have been paid to Hamish Harding who would have turned 59 on Saturday, Shahzada Dawood, 48, and his son Suleman Dawood, 19, Paul-Henri Nargeolet, 77, and Stockton Rush, 61
Emails seen by the BBC show that concerns from an expert over the safety of the Titan sub were dismissed by OceanGate CEO Rush in 2018
Other industry experts have also raised questioned following the "catastrophic implosion"
But an OceanGate investor who has made the trip down to the Titanic told the BBC that the idea Rush had done anything wrong was "disingenuous"
It's emerged the US Navy originally detected “an acoustic anomaly consistent with an implosion” shortly after the Titan lost contact on Sunday
Rear Adm John Mauger says this morning an ROV from the vessel Horizon Artic found the tail cone of the Titan submersible approximately 1600ft from the bow of the Titanic wreck.
And they found additional debris, which is consistent with a catastrophic loss of the pressure chamber.
They immediately notified families.
US Coast Guard and other officials gathered in Boston, Massachusetts, have now started the afternoon press conference on the fate of the Titan submersible.
Stay tuned as we bring you updates as they happen.
You can also watch the press conference by pressing the Play button at the top of the page.
Image source, Dawood familyBritish businessman Shahzada Dawood, 48, was on board with his son, 19-year-old Suleman
As we have been reporting, OceanGate believes the five people who were on the missing Titan submersible have been lost. The five were:
A press conference with the latest official updates on the status of the Titan sub and its passengers is scheduled to begin at 15:00 local time (20:00 BST).
The update comes after the Titan submersible's operating company, OceanGate, just released a statement saying they believe the five crew members to have "sadly been lost."
The US Coast Guard earlier said on Twitter that parts of the sub may have been found amid recently discovered debris.
And here's the full statement from the company:
"We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost.
These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world’s oceans. Our hearts are with these five souls and every member of their families during this tragic time. We grieve the loss of life and joy they brought to everyone they knew.
This is an extremely sad time for our dedicated employees who are exhausted and grieving deeply over this loss. The entire OceanGate family is deeply grateful for the countless men and women from multiple organisations of the international community who expedited wide-ranging resources and have worked so very hard on this mission.
We appreciate their commitment to finding these five explorers, and their days and nights of tireless work in support of our crew and their families.
This is a very sad time for the entire explorer community, and for each of the family members of those lost at sea.
We respectfully ask that the privacy of these families be respected during this most painful time."
OceanGate has just released this statement:
"We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost."
Jonathan Amos
Science correspondent, BBC News
We now have an indication of the nature of the debris reported by the US Coast Guard (USCG) on Twitter.
It is a cover from the aft - or rear - end of the Titan submersible and its landing frame - the section under the sub that enables it to sit on a ship deck or on the seafloor.
This information hasn’t been formally confirmed by the USCG, but we expect it to be when the agency holds a media conference in the next half an hour.
It is bad news. It points to the scenario experts had feared right from the outset - that the Titan had experienced a catastrophic failure of its pressure vessel and imploded.
The pressure at Titanic depth is immense - some 4,000 tons per square metre.
If there was any flaw in the construction of the vehicle, this force would have exploited it.
Search teams will continue to study the area where the debris was found, looking for further fragments.
For the moment, they will just be photographing items. But at some stage, robot subs will almost certainly be tasked with bringing some of the debris to the surface.
A formal mishap inquiry will need to be instigated. It’s not clear whose responsibility that will be because this situation is very unusual, but the US Coast Guard would be a leading candidate.
Titan sub: What debris has been found and what does it mean?
The passengers on board the missing Titan sub would have died instantly and wouldn't even have known there was a problem if the vessel had imploded, a former US Navy physician has said.
The remark came after the BBC was told by a friend of passengers aboard the Titan that the debris discovered includes "a landing frame and a rear cover from the submersible".
Dale Mole, former US Navy physician, said the claim was "indicative of an implosion".
"Death would have been instantaneous," he told the BBC.
Though this outcome would be tragic, Mole said that being stuck inside the vessel would have been a far worse alternative for the Titan crew.
"You can just imagine what it would have been like... it's cold, your oxygen is running out.
"If we can't have them back, this is the best possible scenario."
Let's go back now to this image from the US Coast Guard which shows the search patterns the rescue teams have been covering.
You can see the lines on the image show the parallel pattern which the search has been operating in, and how the search has taken place near the Titanic wreck site.
Image source, .
Chelsea Bailey
Reporting from St John's, Canada
Titanic explorer describes the extreme pressure near the wreck
Here in St John’s the harbour is quiet, a stark contrast to the desperate search mission unfolding hundreds of miles just off the coast.
At the St John’s War Memorial Park, we met Larry Daley, a local Titanic explorer who successfully completed a dive to the shipwreck in 2003 with film director James Cameron.
Just two weeks ago, Daley said he shared a beer with one of the missing crew members, Paul-Henri Nargeolet.
“We weren’t talking about the dives, we were just talking about the old times,” he said, adding that Nargeolet has been a mentor to him for years.
Although he doesn’t have direct experience with OceanGate or the crew running the Titan’s expedition, Daley said he was thinking of those who were aboard.
“My heart goes out to all the crew members, it’s been like that all week.”
Image source, OceanGate ExpeditionsParts of the Titan sub believed to have been located among the debris
We have updated this image to show where the landing frame and rear cover are located on the Titan submersible.
These are the parts that have reportedly been found among debris on the seabed near the Titanic wreck.
Image source, .We know now that a debris field was discovered in the search area for the missing Titan submersible. And we're expecting the coast guard to give an update in the next few hours.
We do have an updated map showing where the different ships involved in the search are currently located in the Atlantic.
We have just had an update from dive expert David Mearns, who says the debris includes "a landing frame and a rear cover from the submersible".
Mearns is a friend of passengers aboard the Titan.
Mearns has told the BBC that the president of the Explorers Club (which is connected to the diving and rescue community), provided this new information.
The debris patch was found by an ROV from the Horizon Arctic, a Canadian commercial vessel which arrived last night near the Titanic wreckage site.
It was loaded with support equipment and was also carrying an Odysseus 6k ROV that can reach depths of 6,000m.
It can also be used to recover items from the bottom of the ocean.
The upcoming press conference will discuss the debris field that the Horizon Arctic's ROV has found.
Callum May
BBC News
Guillermo Söhnlein
The man who co-founded OceanGate with missing submersible pilot Stockton Rush has told BBC News there may have been an “instantaneous implosion” of the craft.
Guillermo Söhnlein was being interviewed as news of the emergence of debris in the Atlantic came in.
He said he would not be surprised if there was something on the surface.
Söhnlein said: “I know that our protocol for lost comms is for the pilot to surface the sub. From the beginning I always thought that’s probably what Stockton would have done.
"In which case it becomes very difficult to find the sub because the surface ship wouldn’t have known it was coming up and wouldn’t have known where to look.
"My biggest fear through this whole thing watching the operations unfold is that they’re floating around on the surface and they’re just very difficult to find.”
He said there was a possibility there had been a catastrophe.
“What I do know is regardless of the sub, when you’re operating at depth the pressure is so great on any sub that if there is a failure it would be an instantaneous implosion. If that’s what happened that’s what would have happened four days ago,” he said.
Söhnlein, who left OceanGate 10 years ago, said he would not have acted differently in the circumstances.
He said: “If anything, I think we need to go back and learn from what’s happening, find out what’s happened, take those lessons and carry them forward.”
Jonathan Amos
Science correspondent, BBC News
This report carries huge caveats.
It may be something, it may be nothing.
But the US Coast Guard has not posted many tweets over the past few days, so it may well be significant.
Speaking to experts this week, many worried that the Titan may have suffered a catastrophic implosion as a result of a hull failure.
Such a scenario could explain the debris. But, again, this report may turn out to be nothing.
The seafloor around the Titanic wreck is littered with all sorts of debris, not least from the great ship itself.
With the breaking news of a debris field being found in the search, US Coast Guard has announced it will hold a press conference at 15:00 local time (20:00 BST).
A statement from the Coast Guard says the Horizon Arctic’s ROV (remotely operated vehicle) found debris on the sea floor near the Titanic wreck.
Rear Adm. John Mauger, the First Coast Guard District commander and Capt. Jamie Frederick, the First Coast Guard District response coordinator, will be speaking.
A debris field has been discovered within the search area by an ROV near the Titanic, the US Coast Guard has just announced.
Experts within the unified command are evaluating the information.
We will bring you more details shortly.
Magellan's chief executive Richard Parkinson
We have some more news about the efforts to send a deepwater survey craft from Jersey to the Atlantic search zone.
As we've been reporting, an attempt to fly out another remotely operated vehicle (ROV) has hit a snag.
The ROV - called Juliet - is owned by Guernsey-based firm Magellan and was loaded late this morning onto a US military aircraft at Jersey Airport.
But the company's chief executive Richard Parkinson confirmed there was "a glitch in getting onboard", where it didn't entirely fit in the aircraft's cargo space.
The ROV has been taken off and will be loaded onto a new plane in the coming hours, according to Parkinson.
"It shouldn't set us back," he added.
Victoria Gill
Science correspondent, BBC News
Remotely operated vehicles (ROVs) that can work in deep water will be able to search the seafloor in an effort to find Titan. But conducting that search will take yet more precious time.
Blair Thornton, professor of marine autonomy, external at the University of Southampton, explained to me that to search a 1km square box with an ROV “you need multiple parallel lines, around 30 or so - if you are using cameras and sonar”.
“Normally, an ROV would travel at a similar speed to a human’s walk, so it is likely to take 5-10 hours to scan that whole area.”
Rather than following a set path, though, the actual operation would respond to - and send the vehicle to inspect - anything the ROV picks up that looks like a potential submersible.
If a robotic vehicle was sent with a line to lift the submersible, that would also be a “difficult operation”, says Prof Thornton.
“The ship needs to make sure they don’t entangle that cable with their main umbilical” - the cable that connects and powers the ROV from the ship.
“And if the search area is amongst the Titanic wreckage,” added Prof Thornton, “then managing the cable so that it doesn’t get entangled would also complicate operations.”